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Date: Fri, 17 Nov 2017 00:59:55 +0100
From: Lukas Wunner <lukas@wunner.de>
To: Marcel Holtmann <marcel@holtmann.org>,
        Gustavo Padovan <gustavo@padovan.org>,
        Johan Hedberg <johan.hedberg@gmail.com>,
        Rob Herring <rob.herring@linaro.org>, Johan Hovold <johan@kernel.org>
Cc: Ronald Tschalaer <ronald@innovation.ch>,
        Sumit Semwal <sumit.semwal@linaro.org>,
        linux-bluetooth@vger.kernel.org, linux-kernel@vger.kernel.org,
        John Stultz <john.stultz@linaro.org>
Subject: Re: [PATCH] Bluetooth: hci_serdev: Init hci_uart proto_lock to avoid
 oops
Message-ID: <20171116235955.GA27601@wunner.de>
References: <CALAqxLVTff-XX7bbQ8a1Pihqe=QW1HDMKST3F3okCV8jY+wGqw@mail.gmail.com>
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On Fri, Nov 17, 2017 at 12:54:53AM +0100, Lukas Wunner wrote:
> John Stultz reports a boot time crash with the HiKey board (which uses
> hci_serdev) occurring in hci_uart_tx_wakeup().  That function is
> contained in hci_ldisc.c, but also called from the newer hci_serdev.c.
> It acquires the proto_lock in struct hci_uart and it turns out that we
> forgot to init the lock in the serdev code path, thus causing the crash.
> 
> John bisected the crash to commit 67d2f8781b9f ("Bluetooth: hci_ldisc:
> Allow sleeping while proto locks are held"), but the issue was present
> before and the commit merely exposed it.  (Perhaps by luck, the crash
> did not occur with rwlocks.)
> 
> Init the proto_lock in the serdev code path to avoid the oops.

Apologies, I botched Gustavo Padovan's and Johan Hedberg's e-mail
address in the To: header, please fix up when replying.

Lukas